Early communication methods and devices where dedicated to one type of communication channel, such as the telegraph and subsequently the telephone. Mobile telephony was originally developed and used for voice dialing. With the second generation of mobile communications, the possibility of sending brief text messages was provided, so called SMS (Short Message Service). SMS enables short messages of generally no more than 140-160 characters in length to be sent and transmitted from a mobile phone, which was introduced in the GSM (Global System for Mobile communications) system and later supported by all other digital-based mobile communications systems. Later, an enhanced transmission service called MMS (Multimedia Messaging Service) was provided, enabling graphics, video clips and sound files to be transmitted via mobile phones. Developed as part of the 3GPP project, MMS phones are generally backward compatible with SMS.
Today, many users of mobile communication systems use their mobile phones for text messaging just as much as for voice dialing. However, the user interfaces of most mobile phones are still configured to be used mainly for dialing, and it takes some maneuvering to initiate a text message when the mobile phone is in a standby mode. Typically, if a telephone number is input by means of the user input interface or fetched from a contact list in the phone, an ordinary speech communication link will be setup upon making a call command. If, on the other hand, the user would like to send a text message, this communication channel has to be selected first.